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                         AUSCERT Security Bulletin

                               ASB-2019.0271
            Microsoft Defender Denial of Service Vulnerability
                             24 September 2019

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              Microsoft Security Essentials
                      Microsoft System Center Endpoint Protection
                      Windows Defender
Operating System:     Windows
Impact/Access:        Denial of Service -- Existing Account
Resolution:           Patch/Upgrade
CVE Names:            CVE-2019-1255  
Member content until: Thursday, October 24 2019

OVERVIEW

        Microsoft has published information about CVE-2019-1255,
        a Denial of Service vulnerability affecting the Microsoft Defender
        family of products. [1]


IMPACT

        The vendor has provided the following information:
        
        "A denial of service vulnerability exists when Microsoft Defender improperly
        handles files. An attacker could exploit the vulnerability to prevent legitimate
        accounts from executing legitimate system binaries.
        
        To exploit the vulnerability, an attacker would first require execution on the
        victim system." [1]


MITIGATION

        Microsoft advises updating the Malware Protection Engine to version
        1.1.16400.2 or later. [1]


REFERENCES

        [1] CVE-2019-1255 | Microsoft Defender Denial of Service Vulnerability
            https://portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2019-1255

AusCERT has made every effort to ensure that the information contained
in this document is accurate.  However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. AusCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.

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Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours 
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
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